Mkwawa University College of Education

Iringa, Tanzania

An Overview Of Our Solution

Cashew is economically important cash in Tanzania. Its production is, however, severely constrained by infestation by sap-sucking insects. The African weaver ant (AWA) is an effective biocontrol agent of pests in coconuts in Tanzania; but its efficacy for the control of sap-sucking insects, has not been investigated in cashew. Field trials were carried out at the Bagamoyo, Kibaha and Mkuranga districts. Results showed that there was a negative correlation between numbers of nests and pest damage. AWA-colonized cashew trees had the lowest shoot damaged by Helopeltis, 4.8 and 7.5% in 2010 and 2011, respectively, compared to 36 and 30% in 2010 and 2011, respectively, in uncolonized cashew trees. The use of fish and hydramethylon increased the number of leaf nests and colonization trails of AWA over the control during off-season.

Who is this solution impacting?

Organization type

Gubernamental

Ecosystem (select all that apply)

Oceans/Coasts

Population impacted

ex. 100,000 people

Size of agricultural area

10,000 ha

Production quantity

50,000 kilos

People employed

100 people

Describe your solution

How have you promoted changes in human activities (or changed your own agricultural practice) to ensure sustainable harvests/food security while also conserving, strengthening and/or restoring biodiversity on your agricultural lands and/or the surrounding environment? (1500 characters max.)

Describe your implementation

• Specific activities i. Quantification of natural enemy Quantification of natural enemy by counting leaf nests per tree and ant trails on main branches. Abundance natural enemy on each tree was quantified all the leaf nests were carefully counted Assessment of damage on shoots and nuts An assessment of damage to flushing shoots and young nuts by Helopeltis spp. and P. wayi, respectively, was conducted on each of the selected cashew trees. A 1m2 quadrat was placed over the shoots approximately 1m above, and each shoots and nuts in each quadrat were carefully inspected and the number of shoots and nuts damaged were recorded separately. ii. Provision of fish and hydramethylon-based baits The abundance of natural enemy was determined once before provision of baits and monthly for four months after provision of baits. • Factors for promotion of change in human activities Field sites were owned by local farmers and they were actively involved from experimental set-up to data collection. Biocontrol was initially considered by farmers irrelevant in the control of the sap-sucking pests in cashew. However, hands on experiences and high yield of nuts tuned their mind. • Enabling conditions Natural occurrence of the predatory weaver ant was one of the enabling conditions. Key success factors i. Suppression of inimical ant species by providing hydramethylon-based baits ensure maximum colonization ii. African weaver ant effective control of sap-sucking pests iii. Conservation of natural enemy by using both fish and hydramethylon-based baits iv. Development of integrated pest and disease management strategy because triadimenol, triadimefon and sulphur does not have detrimental effects on the natural enemy Obstacles The main obstacle was spatial distribution of the predatory ant in cashew tree but this was tackled by placing of rope connections with bamboo sticks or manila thread to enhance widely distribution

External connections

My work was funded by the German Academic Exchange Service (DAAD), the Germany Federal Ministry for Economic Cooperation and Development (BMZ) in collaboration with African Regional Postgraduate Studies in Insect Sciences (ARPPIS) through International Centre of Insect Physiology and Ecology (icipe). I worked hard in developing the concept on Cashew integrated pest management proposal which later enable ARPPIS to attract donors, particularly DAAD. Beside this, I worked under assistance from members of staff from the Arthropod Pathology Unit at Mikocheni Agricultural Research Institute (MARI). I also liaised with key official at the former so called Ministry of Livestock and Fisheries, Tanzania on provision of discarded fresh fish intestines, which were collected from a fish market in Dar-es Salaam. The fish bait was used to enhance and conserve the predatory weaver ant during cashew off-seasons to ensure the survival of the natural enemy. I also worked with farm owners at various villages at Bagamoyo, Kibaha and Mkuranga Districts at the Coast region. Research findings were presented and published in various international platforms such as conferences and peer reviewed journals. Beside this, workshops and seminars were also used to disseminate the findings to other stakeholders including policy makers.

What is the environmental or ecological challenge you are targeting with your solution?

The current management strategy for the key pests of cassava in Tanzania relies on calendar-based applications of pesticides, namely methidathion and diomethoate. Although it can reduce pest damage significantly, disadvantages can also be numerous. These include a reduction in natural enemies and potential pollinators, increased insect resistance to insecticides, environmental pollution and negative effects on the health of the farmers, who often lack the necessary protective gear. A need therefore exists to develop an ecologically sustainable and economically viable integrated pest management (IPM) strategy for the key pests of cassava to ensure income generation and improvement of the livelihood of the cassava farmers in Tanzania. Biocontrol using the parasitoid wasp and an exotic predatory mite, will be evaluated to ensure sustainable management strategies. Currently, there is little information on its establishment and efficacy in the fields since their introduction

Describe the context in which you are operating

I am a Senior Lecturer in the Life Sciences Department, are research and consultancy are among the core functions. I have good experience in using biocontrol at field conditions. I participated in establishment cashew IPM strategy in Tanzania by using African weaver ant (AWA) to control sap-sucking insects, namely Helopeltis spp. and Pseudotheraptus wayi in Tanzania. The aim of this research was therefore to evaluate the efficacy of AWA in the management of these insect pests in the cashew crop at different sites of the Coast region of Tanzania. Colonization levels of AWA trails, varied from 57.1 to 60.6% and from 58.3 to 67.5% in 2010 and 2011, respectively. The mean number of leaf nests per tree varied from five to eight in 2010 and from five to nine in 2011. There was a negative correlation between numbers of nests and pest damage. AWA-colonized cashew trees had the lowest shoot damaged by Helopeltis spp. of 4.8 and 7.5% in 2010 and 2011, respectively, compared to uncolonized cashew trees with 36 and 30% in 2010 and 2011, respectively. I will use skills and knowledge obtained to develop an ecologically integrated pest management strategy for the key pests of cassava

How did you impact natural resource use and greenhouse gas emissions?

Biodiversity was improved by active use of the AWA in cashew fields to control sap-sucking pests. The AWA was found effective in controlling the key cashew pests. The aggressiveness of the predatory ant used to hinder pest to land on the tender shoots of cashew. The presences of the predatory ant also attract homopterans which in turn produce honeydew used by the ant. Various methodology have been used namely, i) quantification of African weaver ant abundance, which was done by counting leaf nests per tree and ant trails on main branches. Twenty cashew trees were selected randomly per site. Abundance natural enemy on each tree was quantified all the leaf nests were carefully counted with the aid of binoculars, and the total number of main branches with natural enemy trails was recorded. Secondly, ii) assessment of damage on shoots and nuts. The effective use of AWA helps to improve biodiversity such as pollinators due to reduction of insecticide.

Language(s)

Swahili and English

Water

Apart from establishment of cashew IPM strategy, soft fungicides such as triadimenol and triadimefon were found to have no effects on the natural enemy compared to sulphur. This means, there was drop out of sulphur which was considered as a major control strategy against powdery mildew disease. Studies have shown a decrease in pH of some acidic soil, which in turn boosts the rate of leaching of valuable nutrients, thereby affecting the productivity of cashew and its companion food crops.

Food Security/Nutrition

Effective control of sap-sucking pests and disease has been implicated to improve livelihood, income and food security for many smallholder farmers engaged in production of cashew nut. The average smallholder cashew farmers cultivates about one to two hectares of cashew trees and were encouraged to intercrop with food crops, mainly cassava, grain staple crops, pineapples and legumes notably pigeon peas. Intercropping was suggested to enable natural perpetuation of the African weaver ants.

Economic/Sustainable Development

Biocontrol of the sap-sucking pests and Powderly mildew disease probably have improve improved economy of the cashew growers. Results showed that nut damage by pest was lowest in African weaver ant-colonized trees with only 2.4 and 6.2% in 2010 and 2011, compared to uncolonized trees with 26 to 21%. This means, more quality nuts were produced in those trees colonized by African weaver ant and hence ensure availability of the market and its price.

Climate

There was no correlation on the finding of the study and climate.

Sustainability

Initially, the development of IPM strategy mainly relies on both grant funding and government. The suggested AWA is facing serious competition from big-headed ant (BHA). It was recommended that, sustainable utilization of the AWA for the cashew pest depend on reduction of competition with BHA. Hydramethylon ant bait was additionally applied at a rate of 3 g tree-1 on AWA-colonized trees to control BHA to ensure a high and stable colonization level of the AWA. The bait was purchased from Kenya and its procurement may need support from external sources to ensure its availability to local farmers. However, in situation where there is no strong competition, manila rope and fish baits could be used, which is cheaper and affordable.

Return on investment

The total cost to implement the aforementioned activities amounted to 25,000 US dollars. Various research materials and equipment were procured in the country and outside the country. It was realistic in terms of the results and investment of 25,000$ due to its significant impact to small-scale holders and environmental conservation as well as improvement of biodiversity.

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How could we successfully replicate this solution elsewhere?

The solution can be replicated in any tree crops elsewhere in the world if the leaves of the host plants are potential for nest construction. Leaves which are in close proximity can be drawn together through the actions of multiple individuals aligning themselves along leaf perimeters and pulling the edges together, or via the formation of a living chain, that bridge gaps and are shortened to draw leaves together. The strategy has been done in Australia by using a different species of weaver ant known as green tree ant at cashew plantation. Key stakeholders can be national agricultural research institute all over the world, universities and grant funding organization. Other stakeholders are extension officers and local farmers. Enhancement of the AWA could be achieved by provision of hydramethylon-based baits. Generally, the total funding required may vary from country to country and about 30,000$ can be considered as minumum funds to replicate the aforementioned solution.

Overview